Rules for usage

Alphanumeric functions

An alphanumeric function can be specified anywhere in the general formats that a data item of class and category alphanumeric is permitted and where the rules associated with the general formats do not specifically prohibit reference to functions, except as noted below.

An alphanumeric function can be used as an argument for any function that allows an alphanumeric argument.

Reference modification of an alphanumeric function is allowed. If reference modification is specified for a function, the evaluation of the reference modification takes place immediately after the evaluation of the function; that is, the function's returned value is reference-modified.

An alphanumeric function cannot be used:

• As a receiving operand of any statement
• Where the rules associated with the general formats require the data item being referenced to have particular characteristics (such as class and category, usage, size, and permissible values) and the evaluation of the function according to its definition and the particular arguments specified would not have those characteristics

National functions

A national function can be specified anywhere in the general formats that a data item of class and category national is permitted and where the rules associated with the general formats do not specifically prohibit reference to functions, except as noted below.

A national function can be used as an argument for any function that allows a national argument.

Reference modification of a national function is allowed. If reference modification is specified for a function, the evaluation of the reference modification takes place immediately after the evaluation of the function; that is, the function's returned value is reference-modified.

A national function cannot be used:

• As a receiving operand of any statement
• Where the rules associated with the general formats require the data item being referenced to have particular characteristics (such as class and category, usage, size, and permissible values) and the evaluation of the function according to its definition and the particular arguments specified would not have those characteristics

Numeric functions

A numeric function can be used only where an arithmetic expression can be specified.

A numeric function can be referenced as an argument for a function that allows a numeric argument.

A numeric function cannot be used where an integer operand is required, even if the particular reference would yield an integer value. The INTEGER or INTEGER-PART functions can be used to force the type of a numeric argument to be an integer.

Integer functions

An integer function can be used only where an arithmetic expression can be specified.

An integer function can be referenced as an argument for a function that allows a numeric argument.

Usage notes:

• A function-identifier cannot be used in the BY REFERENCE phrase of a CALL statement (that is, identifier-2 of the CALL statement must not be a function-identifier).
• The COPY statement accepts function-identifiers of all types in the REPLACING phrase.